Sweet tooth in the genes: study

By Linda Rano

13-May-2008
- Last updated on
19-Jul-2008 at 13:09 GMT

A specific genetic variation may help explain why some people
consume more sugary foods than others.

Confectioners can take heart from these findings which suggest that
in a health conscious world some people may always be tempted by
the sweeter option.
The study, undertaken by researchers at the University of Toronto
and published in Physiological Genomics​, suggested that
individuals with a genetic variation of glucose transporter type 2
(GLUT2) consumed more sugars (sucrose, fructose and glucose)
regardless of age or sex.
The study offers the first evidence of the role that a variation in
the GLUT2 gene has on sugar intake - GLUT2 controls sugar entry
into the cells.
Dr El-Sohemy, the study's senior researcher, said in a statement:
"We have found that a variation in the GLUT2 gene is associated
with a higher intake of sugars among different populations. These
findings may help explain some of the individual variations in
people's preference for sugary foods​."
According to background information by the researchers, glucose
sensing in the brain was thought to be involved in regulating food
intake, but the mechanism was not known.
GLUT2-null mice fail to control their food intake in response to
glucose, suggesting a potential role for this transporter as a
glucose sensor in the brain.
Study details ​
The researchers tested the effects of the genetic variation in two
populations. One population was of older adults who were either
overweight or obese. The other population was of healthy, young and
generally slim adults.
The diets of those in the first population were assessed by
recording all they consumed over a three day period. This exercise
was repeated two weeks later. The participants were also
interviewed face-to-face.
The diets of those in the second populations were assessed via
questionnaire that asked about their food and beverage intake over
a one month period. Additionally, each participant had their blood
taken and their DNA extracted.
The genotype distribution was compared with the food intake data
between individuals with the variation and those without the
variation in GLUT2.
Sweet data​
The DNA samples that carried the variation in GLUT2 were associated
with consuming more sugars in both populations.
The two sets of food records from the older group showed that those
with the variation consumed more sugar than their non-variant
counterparts. At the first visit people with the variation consumed
112 compared to 86 grams of sugar per day (g/d) for their
non-variant counterparts, and 111 g/d at the second visit, compared
to 82 g/d.
Moreover, individuals in the younger population who carried the
variant consumed more sweetened beverages than their non-variant
peers (0.49 versus 0.34 servings per day, respectively) and more
sweets (1.45 vs 1.08 servings per day, respectively).
There were no differences in the amount of protein, fat, starch or
alcohol that was consumed by those with or without the
variant.
"Taken together, our findings show that a genetic variation in
GLUT2 is associated with habitual consumption of sugars, suggesting
an underlying glucose-sensing mechanism that regulates food
intake​," said the researchers.
Dr El-Sohemy noted that the results of this research are
particularly important given the rising rates of obesity and
diabetes in some parts of the world.
Funding ​
The study was funded by the Advanced Food and Materials Network and
the Canadian Institutes of Health Research.
Source: Physiological Genomics ​ May 2008, Volume 33,
pp 355-360
"Genetic variant in the glucose transporter type 2 is
associated with higher intakes of sugars in two distinct
populations"​​Authors: A. El-Sohemy, K.M. Eny,
T.M.S. Wolever, B. Fontaine-Bisson